Wheeled building and construction machine of the mechanical shovel, bulldozer or the like type, having articulated steering

A front-end loader which includes a front carriage and a rear carriage, said front carriage being pivotally connected to said rear carriage so as to be pivotable with respect thereto about a vertical axis,

• said front carriage including:
• a front frame,
• a front axle,
• a pair of front wheels mounted on said front axle,
• a pair of front suspension systems mounting said front frame about said front axle, each of said front suspension systems including a front pivoting lever, which supports said axle and is pivotally connected at one end thereof to said front frame, and an upwardly extending front hydraulic cylinder, which is pivotally connected at one end to said front pivoting lever and at its other end to said front frame,
• a shovel,
• an articulated arm mechanism connected between said shovel and said front frame for lifting said shovel between a lowermost operating position and an uppermost operating position, and
• a first limit switch attached to said front frame which is activated when said articulated arm mechanism lifts said shovel to its uppermost operating position,
• said rear carriage including:
• a rear frame,
• a rear axle,
• a pair of rear wheels mounted on said rear axle,
• a pair of rear suspension system mounting said rear frame above said rear axle, each of said rear suspension systems including a rear pivoting lever, which is pivotally connected at one end to said rear frame, and an upwardly extending rear hydraulic cylinder, which is pivotally connected at one end to said rear pivoting lever and at its other end to said rear frame,
• and wherein said front-end loader also includes:
• a storage tank for hydraulic fluid, and
• a fluid conduit system for supplying hydraulic fluid from said storage tank to said front and rear hydraulic cylinders, said hydraulic fluid system including a pump;
• a magnetic directional valve and a pressure control valve for controlling the supply of hydraulic fluid to said rear hydraulic cylinders, said magnetic directional control valve being connected to said first limit switch so as to cause hydraulic fluid to flow to said rear hydraulic cylinders and cause them to expand when said articulated arm is in its uppermost operating position;
• and at least one transverse stabilizing valve for controlling the flow of hydraulic fluid from said front hydraulic cylinders, thus retarding contraction thereof when subjected to heavy contractive loads.